PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 965 
to the anterior margin. Lateral slopes moderately steep. Beak low; interarea 
short, strongly curved. 
Brachial valve with the greatest convexity in the posterior half. Sulcus shal- 
low, narrow at the umbo, widening anteriorly, but never conspicuots. Anterior 
profile very gently convex ; areas bounding the sulcus very gently swollen. Slopes 
to cardinal extremities gently concave, moderately steep. 
Interior of pedicle valve with a subcordate muscle field ; diductor and adductor 
tracks subequal; median ridge low and short. Brachial valve with short, stout 
brachiophores, narrow and deep notothyrial cavity, and rudimentary cardinal 
process. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Lectotype (brachial valve) .......... ? Fis) 9.2 7.0? y 
Hypotype (pedicle valve 117276a).... 7.3 ? 10.0 8.0? ? 
me Cee Be 7 i710 em ? 10.3 8.0? ? 
a (brachial valve 117276b)... ? 8.5 9.4 6.0 ? 2 
e (aeReaIC) 2. Su. cas Se 6.9 6.6 9.0 6.5 4.2 
Types.—Lectotype : 99259c; paratypes: 99259a,b; figured hypotypes: 117275, 
117276a-e ; 117277d, 117278a,b; unfigured hypotypes: 117276f,g, 117277a-c. 
Horizon and locality—Botetourt formation in Virginia: At the junction of 
Virginia Highways 311 and 114, 4 mile southwest of Catawba, Salem (15’) 
Quadrangle; junction of Virginia Highways 731 and 724, 2 miles northwest of 
Brownsburg, Lexington (15’) Quadrangle; south side of the road 0.2 mile east 
of Strasburg Junction, Strasburg (15’) Quadrangle. 
Arline formation in Virginia: In the quarry at Marion, Marion (T.V.A. 
218-SE) Quadrangle. 
Blockhouse formation in Tennessee: 1.6 miles south-southwest of Toqua 
School, Vonore (T.V.A. 139-SE) Quadrangle. 
Discussion.—The types of this species are impressions of the inner and outer 
surfaces in a soft shale. The species is characterized by a roundly elliptical out- 
line but with distinct shoulders in the posterior region. Costellae and fascicles 
are fine and crowded. It is not so strongly fasciculate as the Friendsville and 
Little Oak species. It is somewhat more finely costellate and with less prominent 
fascicles than P. macrodeltoidea from the Bromide formation. It is not so 
strongly sulcate as P. spinosa from the Edinburg formation. 
PAURORTHIS FASCICULATA Cooper, new species 
Plate 150, B, figures 17-24; plate 151, C, figures 12-18; plate 155, B, figures 11-13 
Deliatreta elegantula Butts (part), Alabama Geol. Surv., Special Rep. 14, pl. 18, fig. 27, 1926. 
Shell of about medium size for the genus, with both valves strongly convex 
and the hinge equal to about seven-tenths the width. Cardinal extremities obtuse. 
Length and width subequal. Lateral margins moderately well rounded; anterior 
margin broadly rounded. Surface fascicostellate with the costellae bundled into 
a number of well-defined and elevated fascicles; 2 fascicles occupy the sulcus of 
